


A Very Good Bad Idea

by theMadStarker



Series: Mad's (mostly) Filthy Tumblr Posts [1]
Category: Marvel Cinematic Universe
Genre: Alternate Universe, Anal Sex, Armor Kink, Barebacking, Father/Son Incest, Incest, Iron cock, M/M, Multi, Shameless Smut, Sibling Incest, Sloppy Seconds, Threesome - M/M/M
Language: English
Status: Completed
Published: 2018-09-24
Updated: 2018-09-24
Packaged: 2019-07-16 14:11:29
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,850
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16087727
Author URL: https://archiveofourown.org/users/theMadStarker/pseuds/theMadStarker
Summary: “Harls, c’mon, we’ve done this so many times,” Peter tried to reason.“Yeah and everytime, Dad caught us and you know he's gonna find out this time too,” Harley said. “We always get punished.”“Yeah… but you like it,” Peter retorted, chin sticking up, all stubborn.--Twins Harley and Peter break into their father's restricted lab. Peter wants to show Harley just how creative Tony can be with the nanites.





	A Very Good Bad Idea

**Author's Note:**

> Prompt: Since you're celebrating, can I ask for some incestuous Teenker, maybe with a little armor kink thrown in?
> 
> Result: Teenker with a lot more armor porn than expected.
> 
> ([Tumblr link](https://the-mad-starker.tumblr.com/post/182376211398/since-youre-celebrating-can-i-ask-for-some))

Peter was dragging Harley to their dad’s lab, leading him by the hand. His younger twin was practically buzzing with energy. It was both adorable and suspicious, but Harley always indulged the younger boy.

His suspicions were confirmed when Peter brought him right to the restricted room that their father used for prototypes.

“Peter,” Harley huffed, exasperated. 

The younger boy immediately turned his puppy eyes towards the older teen.

“Harls, c’mon, we’ve done this so many times,” Peter tried to reason.

“Yeah and everytime, Dad caught us and you know he’s gonna find out this time too,” Harley said. “We always get punished.”

“Yeah… but you like it,” Peter retorted, chin sticking up, all stubborn.

Harley folded his arms, unwilling to give in. “You think Dad doesn’t know that?” He huffed, “pretty sure if we keep doing this, he’ll find something we don’t like… like, for real… You better not be getting me, us, in trouble just cause you want Dad to punish fuck you.”

Peter hadn’t been expecting Harley to resist so much. Usually, his older twin was down to cause some mischief. He had to sweeten the deal then.

The younger teen decided to ignore that last bit. Instead, he stepped closer towards his twin, hands pressing against Harley’s chest. The older boy was wearing one of their dad’s old shirts. Harley immediately squinted at him as though he could read his twin’s intentions. He probably could.

“Do you… remember that time you watched dad fuck me against the side of the building? It was after a mission like a week ago…” Peter asked, looping an arm around Harley’s neck and pulling him close.

Harley knew which night he was talking about. How could he forget? Tony and Peter were the superheroes in the family while Harley kept all the tech up and ready in the safety of the tower.

After one of the missions where Peter was almost hurt, their dad had taken him to some secluded rooftop. Harley had had to watch as Tony’s bleeding edge armor retracted, leaving their father in just his tight undersuit. Peter’s armor had been damaged and the tear had been in such a convenient place that Tony was able to open it up further.

Harley was treated to the sight of his brother and father fucking right there, mouths clashing, bodies writhing together in the aftermath of the battle. It had been so hot… so arousing that Harley had jerked off watching them, listening to the sounds of their Dad grunting and Peter’s soft little cries… At the same time, Harley had felt so left out and no matter how much their Dad had lavished him with attention that night, he still couldn’t help feeling like an outcast.

“Mhmm…” Harley hummed.

He had gotten over his feelings though. He knew that Tony adored him and that his brother loved him just as much.

“Well…” Peter said, reaching up to play with a lock of Harley’s hair. “While we were working on upgrades, I saw a file… I… kinda hacked into the server…”

Peter was in such a playful mood but Harley was getting impatient. Two could play at this game. The older boy wrapped an arm around Peter’s waist, pulling him in until their chests were pressed together.

“Just say it already,” Harley said, running his hand through Peter’s hair. His grip tightened a bit, tugging on the roots. As expected, Peter hissed at the slight sting but he didn’t pull away.

Peter always gave in at the touch of pain.

“Dad made you a suit,” Peter blurted out.

That was not what Harley expected.

“What?” Harley demanded, immediately letting Peter go. He went towards the lock, ignoring how his brother pawed at him from behind.

“Harley…” Peter whined. He pressed against his older brother, hard little cock pressing insistently against Harley’s ass.

“No, you got what you wanted,” Harley said, distracted as he punched in different codes to open the door. He ignored Peter’s huff of irritation.

Tony had kept the locks for these rooms on a separate server so that neither Peter nor Harley would easily crack it through FRIDAY or KAREN. Harley was still pretty sure he could pop it open.

It clicked open on the third try.

“Yes!” Harley cheered, walking right on in with Peter trailing behind him. He turned to grin at his twin, smiling growing even wider when he saw Peter’s disgruntled expression.

“We’re in,” Harley said, “Smile, Petey pie.”

“I’d be happier if you actually took care of this,” Peter said, adjusting his pants.

But he looked around, ignoring the temporary discomfort. Within moments, Peter found what he was looking for and dropped two rather thick bracelets into Harley’s hands. It was made up of multiple links, housing units for the nanites. Each link glowed an effervescent blue and when Harley slipped them on, they fit perfectly. The bracelets were snug on his skin, but they weren’t uncomfortable.

“How do you activate them…?” Harley asked, turning towards his twin. Here, Peter gave a sheepish smile.

“I’m not sure actually…? Mine is kinda just… automatic,” Peter said.

He took Harley’s hand in his own, examining the bracelets. He gave a sigh after some thought. “Dad probably needs to link them to you somehow…”

Coming to the same conclusion, Harley nodded in agreement. “They’re still… awesome. I can’t believe dad made them for me.”

Peter bit his lip, thinking about all the times Harley waved away their father’s suggestion to make a suit. He had done so in the beginning to ease Tony’s worries. It was bad enough that one of his kids were out there, fighting right alongside Iron Man. But as they grew older, Peter saw how the yearning to get more involved only grew. Tony had seen it too, apparently.

Peter pressed up against Harley’s back, hugging him from behind. He rubbed a thumb against the bracelet.

“Dad loves us,” Peter said with unflinching confidence. “This… this just shows how much.”

Then because Peter had always been a horny little shit, he breathed into Harley’s ear. “It’s too bad they’re not attuned to you yet… I kind of wanted to show you something Dad did…”

That immediately piqued Harley’s interest. He turned to face Peter, raising a brow in curiosity.

“What do you mean?”

“Well… You know how Dad can make anything using the nanites…” Peter told him. Casually, his hand slid from its place on Harley’s hip. It traveled across his twin’s taut stomach and slipped down to where Harley was growing hard.

“That night… You never wondered how Dad got me to cum in like 2 minutes?” Peter asked. He licked his lips and Harley’s attention was caught on that slip of pink.

“I just figured you were on edge from the fight,” Harley said. This was a familiar game between them, teasing and playing with each other until someone broke.

Harley reached out and palmed the bulge between Peter’s legs. He grinned when the younger teen gasped, hips pressing forward into Harley’s hand.

“N-No…” Peter stuttered, head falling forward so his face pressed against Harley’s chest. “He… He, um, did something.”

Peter lifted his head and ah, there it was… A faint pink color dusted along his cheeks, familiar brown eyes hooded and wanting.

“Yeah? What did he do, Petey boy?” Harley murmured, continuing to rub his brother’s swollen length. He thought about it for a second, replaying Peter’s earlier words. “Dad fucked you with the armor…?”

That night, Harley hadn’t seen any of the bleeding edge clinging to their father’s body.

“Tell me, Peter,” Harley demanded, “Tell me how Dad fucked you. I was watching… I thought I saw everything, but I guess not. Tell me.”

Peter was clinging onto Harley now, barely stimulating the older boy’s cock. To be honest, he didn’t even need to. Just the memory of his brother and dad fucking was enough to rile Harley up. And now finding out that there had been more going on than what he had seen, Harley was both aroused and so, so curious.

He pushed Peter up against a desk, hands clamped on the younger teen’s waist. They really did have their minds synced though cause not a second later, Peter hopped up. It felt so natural to fall into the space between Peter’s legs, Harley’s hands already undoing and pulling off his jeans.

His brother wore no underwear.

“Of course, you’re not wearing any underwear,” Harley muttered, but it wasn’t unkindly.

Peter blushed, smiling a little slyly. “I mean… is there a point with you and Dad around…?”

Harley’s eyes narrowed. “Dad left this morning. Are you telling me you got to him before…?”

“Don’t be jealous, Harls,” Peter teased, “I mean… you could’ve joined in if you just woke up early enough…”

“Dad’s not a morning person,” Harley pointed out.

Peter shrugged, “He is if you wake him up with a blowjob.”

“Seriously?” Harley asked incredulously. “You could’ve woken me up too.”

In retaliation, he yanked Peter’s jeans off, chuckling when his brother grunted in disapproval. Peter still willingly spread his legs when Harley settled between them.

“We should do this fast…” Peter said, hand pumping his own cock while Harley was unbuttoning his jeans.

He shoved his pants down but didn’t bother pulling them off. He knew Peter was right, that they needed to do this fast before their dad found out.

“Yeah,” Harley agreed. He tugged Peter’s by the hips, moving his ass closer to the edge of the desk

“Did you bring any…? Oh,” Harley had gone to see how tight Peter was only to find that his brother’s hole was wet and prepped for him. Pulling his fingers out left them gleaming in leftover lube and semen. His Dad’s cum…

“God,” Harley breathed out. “Okay, okay, we’re both good to go then.”

“Yeah, hurry up,” Peter said, pulling Harley closer.

They both gasped at the first thrust. Despite his earlier fuck with Tony, Peter’s hole was still so tight and snug around Harley’s erection. Peter, on the other hand, was getting off on the fact that they were doing this, here in their dad’s lab where they shouldn’t be. He wrapped his legs around his brother’s waist, arms pulling Harley closer until Peter was able to kiss him right on his gasping mouth.

While Harley was starting to get a rhythm going, Peter threw his head back, eyes rolling beneath his fluttering lashes. His twin was really going for it, hands grasping and digging into his hips while he pounded away.

“What did Dad do…?” Harley demanded

“Dad… Dad… ugh… he, he used the armor,” Peter said, every thrust making his words stutter. “You didn’t see… Cause… he, mm… used it on his c-cock…”

Harley didn’t pause at all, but the idea made him shove in hard into his brother’s body.

“Like a… cock sleeve or… something…?” Harley panted.

“Yeah…Yeah, exactly… like that,” Peter answered. His eyes fluttered opened and the younger boy nuzzled against Harley’s neck, licking and biting there to get a reaction.

“Shit…” Harley moaned, just imagining it. Did Tony just encase his cock with the nanites while he was fucking Peter or did he add more length…? The number of questions flooded his mind but it was so hard to think while he was buried inside Peter’s tight, wet body.

Peter’s hands tightened on Harley’s shoulders, eyes flicking towards the figure that had just entered.

“Harley…” Peter tried to get his attention, but the other teen was lost in his thoughts and the act of fucking. Harley’s eyes were squeezed shut even as he fucked into Peter’s pliant body.

“God… You can do so much with nanites,” Harley was saying, “How long have you guys been keeping this from me? You gotta tell me what he did, Pete, I’m gonna die just thinking about it…”

“Why don’t I show you then, kiddo?” Tony’s voice said, right into Harley’s ear.

Harley’s eyes flew open, and his hips came to a stuttering halt. But then his father’s hands were right there, clamped right on his hips and urging him to continue.

“Imagine my surprise,” Tony said, “when I got an alert that my two naughty boys were playing with things they shouldn’t be playing with.”

“Dad…” Peter tried to say but ended up moaning when Harley’s cock rubbed right against that sensitive spot… Harley was pretty good about hitting it but their dad’s help, he nailed it almost every thrust.

“Daddy…” Harley tried to sweet talk. “I’m…”

But Tony whispered into his ear. “Shh, baby, I’m not mad… I know why you did it. Don’t worry, baby, I’m just… gonna have a little fun.”

Harley looked over his shoulder, mouth watering when he found his dad wearing a form fitting suit. He had just gotten back then.

“Keep fucking your brother,” Tony told him and Harley obeyed, turning back so that he could give Peter the attention he wanted. Peter was still enjoying it, but their focus was on Tony.

Harley heard the jingle of his dad’s belt being undone, felt Tony tugging his jeans down to expose his ass. And because his dad was always so prepared, Harley wasn’t surprised when he felt Tony’s wet fingers rubbing against his hole.

“Nng,” Harley moaned when Tony started to stretch his hole. He was fucking into Peter’s body with hard, sloppy thrusts, pushing forward and then throwing his ass back to get more of his father’s fingers.

Peter was moaning, legs shaking as Harley pushed himself inside. The older teen had his eyes squeezed shut again, enjoying the sensation of tight heat squeezing his cock and the dextrous fingers rubbing his sensitive walls.

By the time Tony had three fingers in him, Harley felt ready to burst. Peter’s wasn’t any better off, his cock flushed red and leaking against his stomach. He knew better to cum before their Dad said so.

“Dad, please…” Harley moaned, “I can't… please, daddy, please… Put it in already…”

He heard a dark chuckle from behind him but sighed in relief when he felt his dad’s naked cock press hot and hard against his ass.

“Still need you two to learn some stamina…” Tony murmured. But he gave Harley what he wanted, pressing the wet tip of his cock against the boy’s loosened hole.

Harley stilled long enough to let Tony in, groaning at the still considerable stretch when he pushed inside. Then the boy was whining, moaning and gasping as he continued fucking and being fucked by the two people he loved the most.

Then… then something changed. Tony’s cock which had been smoothly sliding in and out of his body… Harley jerked in surprise, his hole clamping down on the bumps and ridges that formed around his father’s cock.

“Yeah… yeah, that’s it…” Peter moaned. He saw the expression of shock and wonder on his brother’s face and immediately knew what had happened. “Freaking nanites…”

Harley choked on his own spot, shoving in hard into Peter’s body and not having the will to move. Instead, he just let Tony fuck into him, his nanite covered cock stimulating his insides and his hole… making Harley feel things he had never felt before. It was both strange and exhilarating, and Harley was crying out, shuddering with each thrust.

Just like Peter that night, Harley didn’t stand a chance, not when the sensations grew too much. He came with a groan, eyes rolling to the back of his head as his father roughly fucked him.

“That’s it, baby… feels good, doesn’t it, Harley baby?” His father purred into his ear. The only response he could give was a whimper, feeling so overstimulated.

Gentle hands pulled him away from his brother. He caught a glimpse of Peter’s hole, dripping with the generous amount of cum Harley had shot into him. He slid to his knees, cock wet and sticky, but definitely spent. His hole felt fucked open and sensitive in a way he had never felt it before.

Tony stood there, his cock so hard and flushed. Harley got a good look at how the nanites covered his father’s erection, seamlessly forming blunt but noticeable bumps and ridges all long Tony’s erection.

He also saw how Peter scrambled forward, practically jumping into their father’s arms.

“My turn…?” Peter asked, breathlessly.

“Bend over, baby,” Tony instructed him. Peter eagerly obeyed, bending over the desk and even spreading himself open, showing off that sloppy hole.

Without hesitation, Tony shoved right in, down to the root. Peter’s back arched, the younger boy moaning as he was fucked full once more. The sound of Tony’s cock fucking into the mess Harley left behind was obscene, wet squelches as he moved through all the lube and cum. The sight was even more arousing, watching his father’s thick cock, covered in gleaming red and silver and gold… All shiny and wet with their combined fluids….

As Harley watched Tony fuck his brother, he massaged his soft cock eager for another round.

“God, I love this family,” Harley muttered to himself.

**Author's Note:**

> Celebrated 500 followers with prompts and finally putting these up on my neglected AO3. (Funny how I started on AO3, got sucked into tumblr, and now I'm writing on Tumblr instead?)
> 
> Feel free to say hi ♡  
> [the-mad-starker.tumblr.com](https://the-mad-starker.tumblr.com)


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